Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
327 AM EST Sat Jan 09 2021

Valid 12Z Sat Jan 09 2021 - 12Z Tue Jan 12 2021


...Southern Rockies/Southern Plains/Lower Mississippi Valley...
Days 1/2...

A potent shortwave trough moving southeast across the Great Basin
early this morning will close into a low as it crosses the
southern Rockies/NM tonight. From there, the system is expected to
shift east across TX Sunday and the Mid-South Monday. Favorable
forcing along the left-exit region of the associated upper jet,
along with low level southeasterly flow from the Gulf of Mexico
across TX will support developing precipitation today along the
eastern slopes of the CO and NM Rockies eastward onto the High
Plains, including southwestern KS and the Panhandle region by this
evening. Deep easterly flow is now expected to be across all of
eastern NM thanks to a southern dip in the forecast track with 00Z
guidance through the evening into the overnight hours will likely
help support periods of heavy snow along the foothills and
mountains. Day 1 snow probabilities are now just moderate for 6 or
more inches for the highest Sangre de Cristo Mountains of CO/NM as
well as the eastern slopes of the Sandia Manzano Mountains of
east-central NM.
As the system continues to move east, precipitation will continue
to spread farther south and east across TX on Sunday. Thermal
profiles suggest precipitation beginning as all snow across much
of Panhandle Plains Sunday morning. With ample moisture in place,
a period of strong forcing through the morning hours is expected
to support a stripe of heavy snows centered around Lubbock where
Day 1.5 snow probabilities are moderately high for 6 or more
inches with moderate probabilities for 4 or more inches from the
southern TX Panhandle and much of west TX then east into North TX.
Dynamic cooling is expected to help draw the rain-snow line
farther east across North TX into eastern TX on Sunday. 00Z
guidance does favor a stripe of moderate accumulations with
accumulating snows are expected to move into the ArkLaTex region
Sunday evening where Day 2 snow probabilities are 20 to 30 percent
for 2 or more inches.


...Washington State...
Day 3...

A potent zonal Pacific jet follows in the wake of a shortwave low
pushing into Vancouver Island late Monday night. Ample Pacific
moisture accompanies this jet with western Washington expected to
receive heavy precipitation. Snow levels of 5000 to 6000ft will
keep the particularly heavy snow limited to areas above the main
passes in the WA Cascades Monday night.


No significant icing is expected Days 1-3.

Jackson